Was it just me or did anyone else picture Melanie as slightly more ethnic than most of these suggestions? I think it would be an interesting casting choice, especially considering the contrast with Pet who is your quintissential blonde haired, fair skinned, pale eyed waif.Speaking of Pet, not to pull from the Twilight cast, but even before she was cast as Jane I always pictured Pet as an older Dakota Fanning (and think about the fact that she'll be at least 16 by the time they get around to filming, if not 17). And we all know that the girl's got the acting chops to pull off a ridiculously old soul in a young body.

i am thinking Izabella Miko (Cammie from Coyote Ugly and she was in the Mr. Brightside video from the Killers) for Wanda/Pet... and I like the Jessica Alba suggestion, but we need someone younger with her same flavor i think...

This may sound odd, but Rose Byrne? Or Saffron Burrows? More indie actresses than any of the aforementioned names.

Eliza Dushku definitely would be awesome, but having seen her in just about everything she's been in, it's hard for me to be impartial. She could definitely pull off alternating tough as Melanie and vulnerable as Wanda. However, there's more screen time in Wanda mode than in Melanie mode, so soft with the ability to play tough rather than the other way around.